Solid-state radiation transducer devices having flip-chip mounted solid-state radiation transducers and associated systems and methods

ABSTRACT

Solid-state radiation transducer (SSRT) devices and methods of manufacturing and using SSRT devices are disclosed herein. One embodiment of the SSRT device includes a radiation transducer (e.g., a light-emitting diode) and a transmissive support assembly including a transmissive support member, such as a transmissive support member including a converter material. A lead can be positioned at a back side of the transmissive support member. The radiation transducer can be flip-chip mounted to the transmissive support assembly. For example, a solder connection can be present between a contact of the radiation transducer and the lead of the transmissive support assembly.

TECHNICAL FIELD

The present technology is related to solid-state radiation transducerdevices and methods of manufacturing solid-state radiation transducerdevices. In particular, the present technology relates to solid-stateradiation transducer devices having flip-chip mounted solid-stateradiation transducers and associated systems and methods.

BACKGROUND

Numerous mobile electronic devices (e.g., mobile phones, personaldigital assistants, digital cameras, and MP3 players) and other devices(e.g., televisions, computer monitors, and automobiles) utilizelight-emitting diodes (“LEDs”), organic light-emitting diodes (“OLEDs”),polymer light-emitting diodes (“PLEDs”), and other solid-state radiationtransducers (“SSRTs”) for backlighting. SSRTs are also used for signage,indoor lighting, outdoor lighting, and other types of generalillumination. To function in such applications, SSRTs generally must bepackaged with other components to form SSRT devices. Conventional SSRTdevices can include, for example, a back-side support for the SSRT(e.g., a mount), a heat sink, device leads, wires connecting the SSRT tothe device leads, an optical component (e.g., a phosphor), and anencapsulant. Each of these components can serve one or more of severalfunctions, including: (1) supporting the SSRT, (2) protecting the SSRT,(3) dissipating heat during operation of the SSRT, (4) modifyingemissions from the SSRT (e.g., changing the color of the SSRTemissions), and (5) integrating the SSRT with the circuitry of externalsystems.

Conventional flip-chip mounting methods generally connect solid-statecomponents to other device components without using wire bonds or otherwires. Typically, in these methods, processing equipment deposits solderbumps onto contacts of the solid-state component, aligns the solderbumps with electrodes of the other device component, places the solderbumps onto the corresponding electrodes of the other device component,and reflows the solder bumps. An underfill material is often disposed inthe space between the mounted solid-state component and the other devicecomponent.

Wire bonding, in contrast to flip-chip mounting, is used to connectconventional SSRTs to other device components. Wire bonding, however,has several disadvantages. For example, wire bonds require a significantamount of physical space. This can be problematic in miniaturizedapplications and applications with multiple SSRTs tightly grouped. Inaddition, wire bond formation is an intricate process requiring time onexpensive equipment. Once formed, wire bonds are among the leastreliable portions of SSRT packaging. For example, differential thermalexpansion of the wires and the SSRTs can stress the wires over time andeventually lead to failure. In view of these and/or other deficienciesof conventional SSRT devices, there remains a need for innovation inthis field.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present disclosure. In the drawings, likereference numerals designate corresponding parts throughout the severalviews.

FIG. 1 is a schematic cross-sectional diagram of an SSRT device inaccordance with an embodiment of the present technology.

FIG. 2 is a schematic cross-sectional diagram of a radiation transducerwithin the SSRT device shown in FIG. 1.

FIG. 3 is a schematic cross-sectional diagram of a system including theSSRT device shown in FIG. 1 on an external system mount of a primarycomponent.

FIG. 4 is a schematic cross-sectional diagram of an SSRT device inaccordance with another embodiment of the present technology.

FIG. 5 is a schematic cross-sectional diagram of an SSRT device inaccordance with another embodiment of the present technology.

FIG. 6 is a schematic cross-sectional diagram of an SSRT device inaccordance with another embodiment of the present technology.

FIG. 7 is a schematic cross-sectional diagram of an SSRT device inaccordance with another embodiment of the present technology.

FIG. 8 is a schematic cross-sectional diagram of an SSRT device inaccordance with another embodiment of the present technology.

FIG. 9 is a schematic cross-sectional diagram of an SSRT device inaccordance with another embodiment of the present technology.

FIG. 10 is a schematic cross-sectional diagram of an SSRT device inaccordance with another embodiment of the present technology.

FIGS. 11A-11E are schematic cross-sectional views illustrating a processof forming an SSRT device in accordance with an embodiment of thepresent technology.

DETAILED DESCRIPTION

Specific details of several embodiments of solid-state radiationtransducer (“SSRT”) devices and associated systems and methods aredescribed below. The terms “SSRT” and “radiation transducer” generallyrefer to die or other structures that include a semiconductor materialas the active medium to convert electrical energy into electromagneticradiation in the visible, ultraviolet, infrared, and/or other spectra.For example, SSRTs include solid-state light emitters (e.g., LEDs, laserdiodes, etc.) and/or other sources of emission other than electricalfilaments, plasmas, or gases. SSRTs can alternately include solid-statedevices that convert electromagnetic radiation into electricity.Additionally, depending upon the context in which it is used, the term“substrate” can refer to a wafer-level substrate or to a singulateddevice-level substrate. A person skilled in the relevant art will alsounderstand that the technology may have additional embodiments, and thatthe technology may be practiced without several of the details of theembodiments described below with reference to FIGS. 1-11.

In certain applications, many functions of conventional SSRT packagesare unnecessary. For example, some conventional SSRT devices areincorporated into systems that have components for adequate support,protection, and heat dissipation, causing such components ofconventional SSRT packages to be redundant. Furthermore, certaincomponents of conventional SSRT packages can cause reliability problems.For example, SSRTs operate at high temperatures and the differentexpansion and contraction of the different components of the SSRTs cancause the failure of connections between the SSRTs and the wiresconventionally used to connect SSRTs to device leads. Severalembodiments of the present technology eliminate wire bonds andunnecessary packaging elements while preserving full functionality witha form of flip-chip mounting.

FIG. 1 is a schematic cross-sectional view of an SSRT device 100 inaccordance with an embodiment of the present technology. In oneembodiment, the SSRT device 100 includes a radiation transducer 102,which is illustrated in more detail in FIG. 2, and a transmissivesupport assembly 104 electrically and mechanically coupled to theradiation transducer by a form of flip-chip mounting. At least a portionof the transmissive support assembly 104 is sufficiently transmissive toradiation that the radiation transducer 102 produces or receives. Thetransmissive support assembly 104 is also sufficiently rigid or of suchmechanical strength that it protects and supports the radiationtransducer 102 during handling and implementation. Conventionalradiation transducers and other solid-state components often areflip-chip mounted to leads on opaque support structures. In contrast, asshown in FIG. 1, embodiments of the present technology can include aradiation transducer 102 flip-chip mounted to a structure that is atleast partially transmissive, such as the transmissive support assembly104. This configuration can eliminate the need for wire bonding and/orback-side support while still providing light modification andcompatibility with the circuitry of external systems.

As shown in FIG. 2, the radiation transducer 102 includes a transducerstructure 106 having a first semiconductor material 108, an activeregion 110, and a second semiconductor material 112. The firstsemiconductor material 108 can be a P-type semiconductor material, suchas P-type gallium nitride (“P-GaN”). The second semiconductor material112 can be an N-type semiconductor material, such as N-type galliumnitride (“N-GaN”). The first and second semiconductor materials 108, 112can individually include at least one of gallium arsenide (GaAs),aluminum gallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP),gallium (III) phosphide (GaP), zinc selenide (ZnSe), boron nitride (BN),aluminum gallium nitride (AlGaN), and/or other suitable semiconductormaterials either instead of or in addition to N-GaN. The active region110 can include a single quantum well (“SQW”), multiple quantum wells(“MQWs”), and/or a bulk semiconductor material. The term “bulksemiconductor material” generally refers to a single grain semiconductormaterial (e.g., indium gallium nitride (“InGaN”)) with a thicknessbetween approximately 10 nanometers and approximately 500 nanometers. Incertain embodiments, the active region 110 can include an InGaN SQW,MQW, or gallium nitride/indium gallium nitride (GaN/InGaN) bulkmaterial. In other embodiments, the active region 110 can includealuminum gallium indium phosphide (AlGaInP), aluminum gallium indiumnitride (AlGaInN), and/or other suitable materials or configurations.

The radiation transducer 102 illustrated in FIG. 2 is a lateral type andincludes first and second contacts 114, 116 connected to the first andsecond semiconductor materials 108, 112, respectively. The first andsecond contacts 114, 116 can include a metal, such as nickel (Ni),silver (Ag), copper (Cu), aluminum (Al), and tungsten (W). A dielectricmaterial 118 isolates the second contact 116 from the firstsemiconductor material 108 and the active region 110. The dielectricmaterial 118 can include silicon dioxide (SiO₂) and/or silicon nitride(SiN). The radiation transducer 102 can also include a carrier substrate120 at the second semiconductor material 112. The carrier substrate 120can be, for example, a metal (e.g., nickel (Ni) or gold (Au)), silicon,aluminum nitride, or sapphire. The radiation transducer 102 has anactive side 122 and a back side 124. To improve emission from the activeside 122 when the carrier substrate 120 is not reflective, a reflectorcan be positioned between the second semiconductor material 112 and thecarrier substrate 120, such as a reflector including a metal (e.g.,nickel (Ni) or gold (Au)).

Although illustrated in connection with a particular radiationtransducer 102 shown in FIG. 2, embodiments of the disclosed technologycan be used with virtually any radiation transducer 102, includingradiation transducers having various contact structures (e.g., verticaland lateral radiation transducers) as well as radiation transducershaving various sizes and shapes. Embodiments of the present technologyalso can be used with either single radiation transducers or multipleradiation transducers (e.g. one or more arrays of radiationtransducers). The carrier substrate 120 is also optional. When present,the carrier substrate 120 is generally at the back side 124 of theradiation transducer 102 (as in the radiation transducer shown in FIG.2), but in some cases, the carrier substrate can be at the active side122 of the radiation transducer. When positioned at the active side 122of the radiation transducer 102, the carrier substrate 120 can be madeof a transparent material, such as sapphire.

In several embodiments of the present technology, the back side 124 ofthe radiation transducer 102 is an external surface of the SSRT device100. This is different than conventional SSRT devices in which the SSRTis fully enclosed within packaging. Considering this, it can be usefulto incorporate an SSRT 100 having a carrier substrate 120 made from amaterial well suited for direct exposure to an external system, such asa material with good corrosion resistance and durability. It also can beuseful for the carrier substrate 120 to include a material of highthermal conductivity for improved heat dissipation. Examples ofparticularly suitable materials for the carrier substrate 120 includegold (Au) and aluminum nitride (AlN).

Referring back to FIG. 1, the illustrated embodiment of the SSRT device100 further includes an underfill 126 between the radiation transducer102 and the transmissive support assembly 104. The transmissive supportassembly 104 includes a transmissive support member 128 and an edgereflector 130. The transmissive support member 128 can include a matrixmaterial 132, such as a polymeric material, and a converter material134, such as a cerium (III)-doped yttrium aluminum garnet (YAG) at aparticular concentration in the matrix material for emitting a range ofcolors from green to yellow and to red under photoluminescence. In otherembodiments, the converter material 134 can include neodymium-doped YAG,neodymium-chromium double-doped YAG, erbium-doped YAG, ytterbium-dopedYAG, neodymium-cerium double-doped YAG, holmium-chromium-thuliumtriple-doped YAG, thulium-doped YAG, chromium (IV)-doped YAG,dysprosium-doped YAG, samarium-doped YAG, terbium-doped YAG, and/orother suitable wavelength conversion materials. Emissions (e.g., light)from the transducer structure 106 (FIG. 2) can irradiate the convertermaterial 134, and the irradiated converter material can emit a light ofa certain quality (e.g., color, warmth, intensity, etc.). The edgereflector 130 can prevent or diminish light piping and emission lossthrough the edges of the transmissive support assembly 104. Suitablematerials for the edge reflector 130 include silver (Ag) and gold (Au).

In the embodiment of the SSRT device 100 illustrated in FIG. 1, thetransmissive support assembly 104 includes a single transmissive supportmember 128 and a single type of converter material 134 in thetransmissive support member. Other embodiments can have more than onetransmissive support member 128 within the transmissive support assembly104. Each transmissive support member 128 can have no converter material134, one converter material, or multiple converter materials. Forexample, several embodiments of the present technology can be configuredas red-white-green-blue (“RWGB”) devices. The transmissive supportassembly 104 of such embodiments can include three converter materials134. A first converter material 134 can be a yellow phosphor that mixeswith blue light emitted by the transducer structure 106 to form a whitepixel. Second and third converter materials 134 can be red and greenphosphors, respectively, that fully convert the blue light from thetransducer structure to form corresponding red and green pixels. Thetransducer structure 106 can create blue emissions without conversion.RWGB devices can be used in displays, monitors, televisions, and/orother suitable multi-color applications.

The transmissive support assembly 104 can also include conductiverouting having a plurality of leads 136 patterned on the transmissivesupport member 128. The leads 136, for example, can be copper (Cu) oraluminum (Al) traces with pads that are photo-patterned on a back side138 of the transmissive support member 128. In several embodiments, theleads each include two or more pads sized to receive a solder bump and atrace between the pads. The transmissive support assembly 104 canfurther include a solder mask 140 patterned over the leads 136 and theback side 138 of the transmissive support member 128 to have openingsover the pads of the leads 136. The solder mask 140 can includedielectric material, such as silicon dioxide (SiO₂), silicon nitride(SiN), and/or other suitable dielectric materials.

The radiation transducer 102 is effectively packaged on the transmissivesupport assembly 104. For example, the SSRT device 100 can includesolder connections 142 between bond pads (not shown) on the active side122 of the radiation transducer 102 and the leads 136 on the back side138 of the transmissive support member 128, and external solder bumps144 partially isolated within the openings of the solder mask 140. Inthe illustrated embodiment, the external solder bumps 144 are the onlyexternal electrodes for the SSRT device 100. Other embodiments can haveadditional external electrodes, or another electrode configuration. Forexample, in several embodiments, the radiation transducer 102 is avertical device and the back side 124 of the radiation transducerincludes an additional external electrode. These embodiments can includeadditional solder on the back side 124 of the radiation transducer 102to facilitate electrical connection of the back side of the radiationtransducer to an external system.

The solder connections 142 and external solder bumps 144 can include anysolder material known in the semiconductor fabrication arts. In severalembodiments, the solder connections 142 and external solder bumps 144include gold (Au), nickel (Ni), copper (Cu), aluminum (Al), tungsten(W), and/or other suitable electrically conductive materials. The solderconnections 142 and external solder bumps 144 also can include aconductive polymer (e.g., polyacetylene, polypyrrole, or polyaniline).Since the solder connections 142 and leads 136 can be positioned on theactive side 122 of the radiation transducer 102, output from the SSRTdevice 100 can potentially be improved by the use of transparentconductive materials. For example, the solder connections 142 and/orleads 136 can include indium tin oxide (ITO).

The underfill 126 surrounds the solder connections 142 and occupies theremaining space between the radiation transducer 102 and thetransmissive support assembly 104. The underfill 126 can, for example,absorb stress caused by differential thermal expansion and contractionof the radiation transducer 102 and the transmissive support assembly104. This prevents such expansion and contraction from causing damage tothe solder connections 142, which could result in device failure.Suitable materials for the underfill 126 include substantially opticallyclear materials, such as substantially optically clear silicone orsubstantially optically clear epoxy. In several embodiments, theunderfill material is the same as the matrix material 132 of one or moretransmissive support members 128 of the transmissive support assembly104.

FIG. 3 illustrates the SSRT device 100 connected to one example of anexternal system mount 146 of a primary component 147 (e.g., a light,electrical appliance, vehicle or other product into which the SSRTdevice 100 can be integrated). The external system mount 146 includes asubstrate 148, a mount 150, and two system electrodes 152. To connectthe SSRT device 100 to the external system mount 146, the SSRT devicecan be placed on the external system mount such that the external solderbumps 144 are aligned with the system electrodes 152. The externalsolder bumps 144 then can be reflowed. The radiation transducer 102 canrest on the mount 150, be bonded to the mount (e.g. with adhesive), orbe suspended near the mount. In some external system mounts 146, themount 150 includes a cradle or other recess for supporting the radiationtransducer 102. The external system mount 146 also can include no mount150 and the solder bonds formed from reflowing the external solder bumps144 can provide mechanical support for the SSRT device 100.

In the illustrated SSRT device 100 having a lateral-type radiationtransducer 102, one of the external solder bumps 144 is a P-typeconnection and the other external solder bump is an N-type connection.As shown in FIG. 3, these external solder bumps 144 are connected toP-type (+) and N-type (−) system electrodes, respectively. Inembodiments in which the radiation transducer 102 includes a back-sidecontact, the mount 150 can include an additional system electrode. Forexample, in embodiments including a vertical-type radiation transducer102, a back-side contact of the radiation transducer can be soldered toa system electrode on or in place of the mount 150. In such embodiments,the system electrode connected to the back side 124 of the radiationtransducer 102 can be P-type and the other electrodes can be N-type orthe system electrode connected to the back side of the radiationtransducer can be N-type and the other electrodes can be P-type.

The first and second contacts 114, 116 of the radiation transducer 102shown in FIG. 2 are substantially coplanar on the active side 122 of theradiation transducer. This configuration facilitates flip-chip mountingbecause solder connections 142 of substantially the same size can beused to connect two or more substantially coplanar contacts on onesurface to two or more substantially coplanar leads on another surface.This feature, however, is not necessary. Several embodiments includeradiation transducers 102 having non-coplanar contacts on the activeside 122. In these embodiments, different sized solder connections 142can exist between the radiation transducer 102 and the leads 136 of thetransmissive support assembly 104. Alternatively, other portions of theSSRT device 100 can be formed nonsymmetrically to accommodate differentcontact positions on the radiation transducer 102. For example, theleads 136 can have different thicknesses or be placed on one or morespacer layers.

The external solder bumps 144 of the SSRT device 100 are substantiallysymmetrical and extend away from the transmissive support assembly 104to a plane substantially even with the back side 124 of the radiationtransducer 102. This configuration is suitable for connecting the SSRTdevice 100 to an external system mount 146 in which the mount 150 andthe system electrodes 152 are substantially coplanar, such as theexternal system mount 146 shown in FIG. 3. For connecting to externalsystem mounts 146 having different configurations, the external solderbumps 144 can be differently sized, such as to extend to differentvertical positions relative to the back side 124 of the radiationtransducer 102. Other portions of the SSRT device 100 also can beconfigured differently with features such as those described above foraccommodating contacts of the radiation transducer 102 having differentvertical positions. The horizontal positions of the external solderbumps 144 can be easily modified, for example, by extending orshortening the leads 136. For greater versatility, the external solderbumps 144 also can be replaced with other electrical connection types,such as wires. Wires used in place of the external solder bumps 144 canbe more reliable than wires used in conventional SSRT devices to connectSSRTs to other device components. Wires used in place of the externalsolder bumps 144, for example, can be compositionally similar to theleads 136, and therefore not be subject to stress from differentialthermal expansion.

In several embodiments of the present technology, the transmissivesupport assembly 104 is formed separately from the radiation transducer102. In contrast, transmissive components of many conventional SSRTdevices are formed directly on the radiation transducers (e.g., bydepositing a material onto a surface of a radiation transducer). Formingthe transmissive support assembly 104 separately can be advantageousbecause certain formation processes, such as molding, are difficult toexecute directly on a radiation transducer surface. Molding inparticular can be used to form portions of transmissive supportassemblies 104, such as the transmissive support member 128 shown inFIG. 1, having a variety of useful shapes and surface characteristics.Transmissive components formed directly on radiation transducers can belimited in size and shape in conventional designs. In contrast,embodiments of the present technology can include transmissive supportmembers 128 for which the size and shape are determined independently ofthe size and shape of the radiation transducer 102 or the number ofradiation transducers in an array. Transmissive support members 128 ofthese embodiments, therefore, often can be sized and shaped according tothe specifications of secondary optical components or other structuresof external systems into which the SSRT devices 100 will beincorporated. For example, some external systems include reflectorcavities, Fresnel lenses, and/or pillow lenses that modify emissionsfrom the SSRT device 100. Transmissive support members 128 of severalembodiments of the present technology can be sized and shaped accordingto the specifications of such structures so that the SSRT devices 100integrate effectively with such structures. For example, thetransmissive support members 128 of several embodiments of the presenttechnology are sized and shaped to support or fit inside certaincomponents of external systems, such as certain secondary opticalcomponents.

As shown, for example, in FIG. 1, the transmissive support assembly 104can be spaced apart from the radiation transducer 102 with solderconnections 142 and the underfill material 126 in the intervening space.Spacing transmissive support members 128 apart from the radiationtransducers 102 in this manner can be advantageous. For example, it canbe difficult to form transmissive components that are relatively thick,dimensionally uniform, and/or uniform in converter concentration whenforming such components directly on radiation transducer surfaces.Multiple radiation transducers in an array can also be mounted to atransmissive support member 128 that is spaced apart from the radiationtransducer array. Furthermore, some materials useful for transmissivecomponents, such as certain polymers, can be darkened or otherwisedamaged by heat from direct contact with radiation transducers duringoperation. Spacing these materials apart from the radiation transducerscan prevent such damage from occurring.

FIG. 4 illustrates an SSRT device 200 including a transmissive supportassembly 202 having a transmissive support member 204 that issubstantially hemispherical and extends over substantially the entiresurface of the SSRT device. FIG. 5 illustrates an SSRT device 250including a transmissive support assembly 252 having a transmissivesupport member 254 that is substantially planar near the edges andsubstantially hemispherical over a central portion of the SSRT device.

In the SSRT devices 200, 250 of FIGS. 4 and 5, the transmissive supportmembers 204, 254 include substantially uniform distributions ofconverter material 134. In other embodiments, the distribution ofconverter material 134 in the transmissive support members can benon-uniform. FIG. 6 illustrates an SSRT device 300 similar to the SSRTdevice 200 of FIG. 4, but with a transmissive support assembly 302having a transmissive support member 304 including a non-uniformdistribution of converter material 134. FIG. 7 illustrates an SSRTdevice 350 similar to the SSRT device 250 of FIG. 5, but with atransmissive support assembly 352 having a transmissive support member354 including a non-uniform distribution of converter material 134. Thetransmissive support member 304 of FIG. 6 includes a first portion 306having a low concentration of converter material 134 or no convertermaterial and a second portion 308 having a relatively high concentrationof converter material. Similarly, the transmissive support member 354 ofFIG. 7 includes a first portion 356 having a low concentration ofconverter material 134 or no converter material and a second portion 358having a relatively high concentration of converter material. In FIGS. 6and 7, the division between the first portions 306, 356 of thetransmissive support members 304, 354 and the second portions 308, 358of the transmissive support members 304, 354 are indicated with dashedlines because the first and second portions are within the sametransmissive support members. Other embodiments can include separatetransmissive support members having different concentrations ofconverter material, such as separate transmissive support membersresembling the first portions 306, 356 and second portions 308, 358 ofthe transmissive support members 304, 354 shown in FIGS. 6 and 7.

FIG. 8 illustrates an SSRT device 400 having a transmissive supportassembly 402 including a first transmissive support member 404 and asecond transmissive support member 406. The first transmissive supportmember 404 includes a converter material 134. The second transmissivesupport member 406 is a transition layer positioned between theradiation transducer 102 and the first transmissive support member 404.Other embodiments can include a transition layer as the onlytransmissive support member, a transition layer at a different positionwithin the transmissive support assembly, or multiple transition layerswithin the transmissive support assembly. The second transmissivesupport member 406 can be made of a material with a refractive indexbetween the refractive index of the transducer structure 106 of theradiation transducer 102 and a refractive index of the firsttransmissive support member 404 positioned further from the radiationtransducer than the second transmissive support member. In severalembodiments, a transmissive support member that is a transition layerhas a refractive index from about 1.6 to about 1.9. Passing emissionsfrom a radiation transducer 102 through such a material generallyimproves the output of the SSRT device 400 by reducing refraction andassociated back reflection. Examples of suitable materials for thesecond transmissive support member 406 include glass, triacetylcellulose, polyethylene terephthalate, and polycarbonate.

In several embodiments of the present technology, the exterior surfaceof or an interface within the transmissive support assembly can beroughened and/or textured. FIG. 9 illustrates an SSRT device 450 havinga transmissive support assembly 452 with a transmissive support member454 having a textured surface 456. Including a textured surface, such asthe textured surface 456, can improve the output from the SSRT device450 by, for example, reducing the total internal reflection within thetransmissive support assembly 452. The texturing can include regularpatterning, random patterning, micropatterning, and/or macropatterning.Methods for texturing include photolithography, etching, and abrasionafter the transmissive support member is formed. Molding, discussed ingreater detail below, also can be used to alter the surfacecharacteristics of a transmissive support member in embodiments of thepresent technology

FIG. 10 illustrates an SSRT device 500 including an encapsulant 502around the majority of the back side of the SSRT device. The encapsulant502 can protect the radiation transducer 102 and other portions of theSSRT device 500 as well as dissipate heat from the radiation transducerduring operation. Suitable materials for the encapsulant 502 includepolymeric materials, such as clear and opaque epoxies. The externalsolder bumps 504 are larger than the external solder bumps 144 shown inFIGS. 1 and 3-9 so as to extend beyond the outer surface of theencapsulant 502. When connecting the SSRT device 500 to an externalsystem mount 146, the bottom surface of the encapsulant 502 can rest onthe mount 150, be bonded to the mount (e.g. with adhesive), or besuspended near the mount. If the radiation transducer 102 includes aback-side contact, an electrode can extend through the encapsulant 502for connection to an external electrode.

FIGS. 11A-11E illustrate a process of forming the SSRT device 100 inaccordance with an embodiment of the present technology. FIG. 11A showsa stage of the process after the transmissive support member 128 hasbeen formed on a formation substrate 550. The formation substrate 550can be any substrate rigid enough or of sufficient mechanical strengthto support the transmissive support member 128. For example, theformation substrate 550 can be a silicon wafer, a polymer, glass orother type of wafer or sheet. The transmissive support member 128 can beformed on the formation substrate 550 by a technique such as molding,ink jetting, spin coating, chemical vapor deposition (“CVD”), orphysical vapor deposition (“PVD”). With exceptions, molding typically iswell suited for making thicker transmissive support members 128, such astransmissive support members with thicknesses greater than about 150microns. Spin coating and other deposition processes typically arebetter suited for making thinner transmissive support members 128, suchas those with thicknesses less than about 150 microns. Thickertransmissive support members 128 with a converter material 134 typicallycan achieve the same level of conversion as thinner transmissive supportmembers that have lower concentrations of converter material. Thus,thicker transmissive support members 128 having a converter material 134can be useful when thinner transmissive support members would requireconcentrations of converter material beyond saturation levels. As analternative to making the transmissive support member 128 with aconverter material 134, prefabricated transmissive support membershaving a converter material can be purchased, such as from Shin-EtsuChemical Co., Ltd. (Tokyo, Japan).

In several embodiments of the present technology, a precursor materialis deposited on a formation substrate 550 and then cured (e.g.,ultrasonically or thermally) to form one or more transmissive supportmembers 128 of the transmissive support assembly 104. Suitable precursormaterials include liquids and/or powders as well as polymeric and/ornonpolymeric materials. Suitable precursor materials for transmissivesupport members 128 with a converter material 134 include epoxy resinscontaining phosphor particles. Rather than simple deposition, theprecursor material also can be molded, such as injection molded. Ifmolding is used, the formation substrate 550 can be a portion of a mold.Molding allows the formation of transmissive support members having avariety of shapes and sizes, such as the transmissive support members128, 204, 254, 304, 354, 404, 406 shown in FIGS. 1 and 4-8. Molding alsocan be used to form transmissive support members having differentsurface characteristics, such as the transmissive support member 454shown in FIG. 9, which has a textured surface 456. A texture pattern,for example, can be incorporated into a portion of a mold.

Some molding techniques can be used to form transmissive support membershaving different portions with different concentrations of convertermaterial 134, such as the transmissive support members 304, 354 of FIGS.6 and 7. For example, a precursor material can be molded and thenallowed to rest during a period prior to curing while gravity causesparticles of converter material 134 to settle. Using gravity, theorientation of the molded precursor material relative to the directionof the force of gravity during the period prior to curing determines theconfiguration of the final transmissive support member. Alternatively,the molded precursor material can be placed in a centrifuge and theorientation of the molded precursor material relative to the directionof the centrifugal force during the period prior to curing determinesthe configuration of the final transmissive support member. Suitablemachines for molding transmissive support members for use in embodimentsof the present technology include TOWA Corporation (Kyoto, Japan) modelsLCM1010 and FFT1030W.

FIG. 11B shows a stage in the process after the leads 136 are formed onthe transmissive support member 128, and FIG. 11C shows a stage afterthe solder mask 140 has been formed on the leads 136. The leads 136 andthe solder mask 140 can be formed using any deposition and patterningtechnique known in semiconductor fabrication arts, such as CVD, PVD, oratomic layer deposition (“ALD”) followed by photolithography.

Separately from the steps shown in FIGS. 11A-11C, solder balls aredeposited onto contacts on the active side 122 of the radiationtransducer 102. The radiation transducer 102 is then flipped and placedon the structure shown in FIG. 11C, with the solder balls of theradiation transducer aligned with the leads 136. The solder is thenreflowed (e.g., ultrasonically or thermally) resulting in the structurehaving the solder connections 142 shown in FIG. 11D. Alternatively, thesolder balls can be placed on the leads 136 and the radiation transducer102 placed onto the solder balls. As shown in FIG. 11E, the underfill126 is then introduced into the area between the transmissive supportmember 128 and the radiation transducer 102. This can be done, forexample, by injecting heated underfill material from the side of thestructure shown in FIG. 11D and then curing the underfill material, suchas with microwave radiation. The external solder bumps 144 are thendeposited in the openings of the solder mask 140. Finally, the formationsubstrate 550 is separated from the transmissive support member 128 toform the SSRT device 100 shown in FIG. 1. Although not illustrated inFIGS. 11A-11E, the edge reflector 130 can be formed, for example, byetching trenches between and around individual SSRT devices within anarray of SSRT devices and depositing a reflective material (e.g., silver(Ag)) into the trenches prior to forming the solder mask 140. Oncecompleted, the array of SSRT devices can be diced along the centers ofthe trenches such that a portion of the reflective material remains onthe edges of each SSRT device.

SSRT devices 100 according to embodiments of the present technology canbe made using a variety of processes other than the process describedwith reference to FIGS. 11A-11E. For example, in several embodiments, noformation substrate 550 is used. Instead, the SSRT device 100 can beformed on a pre-formed, self-supporting transmissive support member 128(e.g., a transmissive support member including a converter material 134or a transmissive support member that is a transition layer). When aformation substrate 550 is used, the formation substrate can be removedat various times during the process. For example, the transmissivesupport assembly 104 can be formed on a formation substrate 550 and thenremoved from the formation substrate prior to mounting the radiationtransducer 102. Furthermore, the radiation transducer 102 can be mountedto the transmissive support assembly 104 or the transmissive supportassembly can be mounted to the radiation transducer.

From the foregoing, it will be appreciated that specific embodiments ofthe present technology have been described herein for purposes ofillustration, but that various modifications may be made withoutdeviating from the technology. For example, the embodiments illustratedin FIGS. 1-11 include two solder connections 142. Other embodiments ofthe present technology can include one, three, four, five, or a greaternumber of solder connections 142. Certain aspects of the presenttechnology described in the context of particular embodiments may becombined or eliminated in other embodiments. For example, thetransmissive support assembly 104 of the embodiment shown in FIG. 1 caninclude the second transmissive support member 406 of the embodimentshown in FIG. 8. Furthermore, while advantages associated with certainembodiments of the present technology have been described in the contextof those embodiments, other embodiments may also exhibit suchadvantages, and not all embodiments need necessarily exhibit suchadvantages to fall within the scope of the technology. Accordingly, thedisclosure and associated technology can encompass other embodiments notexpressly shown or described herein.

I claim:
 1. A solid-state radiation transducer (SSRT) device,comprising: a radiation transducer including a first semiconductormaterial, a contact electrically connected to the first semiconductormaterial, a second semiconductor material spaced apart from the firstsemiconductor material, and an active region between the firstsemiconductor material and the second semiconductor material; and atransmissive support assembly attached to the radiation transducer, thetransmissive support assembly including a transmissive support memberhaving a back side facing toward the radiation transducer, thetransmissive support member including a cured matrix material andparticles of converter material disposed within the cured matrixmaterial, and a lead at the back side of the transmissive supportmember, the lead being electrically connected to the contact, whereinthe radiation transducer is flip-chip mounted to the transmissivesupport assembly.
 2. The SSRT device of claim 1, wherein thetransmissive support member has a textured front side facing away fromthe radiation transducer.
 3. The SSRT device of claim 1, wherein thetransmissive support member has a convex front side facing away fromradiation transducer.
 4. The SSRT device of claim 1, further comprisinga substantially optically-transparent underfill material between theradiation transducer and the transmissive support assembly.
 5. The SSRTdevice of claim 1, wherein: the lead is a first lead; the contact is afirst contact; the radiation transducer includes a second contactelectrically connected to the second semiconductor material; thetransmissive support assembly includes a second lead at the back side ofthe transmissive support member, the second lead being electricallyconnected to the second contact; the SSRT device further comprises afirst solder connection extending between the first contact and thefirst lead, and a second solder connection extending between the secondcontact and the second lead; and an interface between the first solderconnection and the first lead is substantially coplanar with aninterface between the second solder connection and the second lead. 6.The SSRT device of claim 1, wherein: the transmissive support member isa first transmissive support member; the transmissive support assemblyincludes a second transmissive support member positioned between thefirst transmissive support member and the radiation transducer; and thesecond transmissive support member has a refractive index between arefractive index of the radiation transducer and a refractive index ofthe first transmissive support member.
 7. The SSRT device of claim 6,wherein the second transmissive support member has a refractive indexfrom about 1.6 to about 1.9.
 8. The SSRT device of claim 1, wherein: thetransmissive support member includes a first portion having a firstconcentration of the particles of the converter material and a secondportion having a second concentration of the particles of the convertermaterial; and the first concentration is higher than the secondconcentration.
 9. The SSRT device of claim 1, wherein the radiationtransducer is a light-emitting diode.
 10. The SSRT device of claim 1,wherein the radiation transducer is a photovoltaic cell.
 11. The SSRTdevice of claim 3, wherein transmissive support member is hemispherical.12. The SSRT device of claim 4, wherein the underfill material is thesame as the matrix material.
 13. The SSRT device of claim 8, wherein thefirst portion of the transmissive support member is closer to theradiation transducer than the second portion of the transmissive supportmember.
 14. The SSRT device of claim 1, wherein the transmissive supportmember is molded.
 15. The SSRT device of claim 1, wherein the convertermaterial is a phosphor material.
 16. The SSRT device of claim 1, whereinthe matrix material is polymeric.
 17. The SSRT device of claim 1,wherein the matrix material is an epoxy.
 18. The SSRT device of claim 1,wherein the transmissive support member is spaced apart from theradiation transducer.